Practical Applications of Computational Studies of the Glycosylation Reaction
Bibliographic record
Abstract
A qualitative summary of our canonical vector representation of the conformations of six membered rings and its quantitative application to sugar pyranose rings is presented first. This representation is illustrated for the results of Density Functional Theory (DFT) optimized structures of per O-methylated D-lyxo, D-manno and D-gluco-configured oxacarbenium ions where two conformers are consistently found. Nucleophilic attack modelled with methanol is found to lead to intramolecular hydrogen bonding from the hydroxylic proton to electronegative oxygens of the oxacarbenium ion. As well, the ring conformation is found to change with the C-5-O-5--C-1-C-2 torsion angle moving from nearly planar in the isolated cations to more negative values in the case of α-approach and to more positive values for β-attack. This can be favorable or unfavorable depending on the protecting groups present with for example 4,6-benzylidene protection favoring β-attack with D-manno-configured ions whereas for D-gluco-configured ions α-approach is favorable. Extending the DFT studies to 2-O-acetyl analogues finds similar pairs of cations and raises the important issue of the order of ring inversion or 0-2 bond rotation during the formation of ring inverted dioxolenium ions which in some cases are calculated to be very stable. Finally, an example using complex constraints is described which led to the design and development of 2,6-dimethylbenzoyl and 2,6-dimethoxybenzoyl as O-2 protecting groups which greatly minimize the acyl transfer side reaction.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".